Does anyone have an idea of where can I find a copy of the bitcoin source code. I mean doesn't it supposed to be open source, where is the open source project for bitcoin so I can read the code.
However, for miners the story is a bit different. If you're a miner you kind of need to use bitcoind. Otherwise bad things might happen such as the blockchain fork from last March: http://bitcoinmagazine.com/3668/bitcoin-network-shaken-by-blockchain-fork/
There is also helpful documentation such as the detailed Bitcoin spec for the P2P layer at bitcoin.org.